The present invention relates to a clutch drum for use in automatic transmissions.
Manual and automatic transmissions are used in motor vehicles. An automatic transmission has planetary gears for providing suitable gear ratios, and clutches for connecting driving members of the gear train. Such clutches have clutch drums of a cylindrical shape. The clutch drum is formed, on its cylindrical wall, axially extending spline grooves for engaging with driving plates or driven plates of the clutch.
Recently, there has been a tendency toward diameter reduction in automatic transmissions because an automatic transmission of a small diameter is advantageous to automobile layout. In a conventional arrangement, the driving and driven plates are disposed around the outer periphery of the planetary gear. This conventional arrangement is detrimental to the diameter reduction of automatic transmissions. There is known another arrangement in which the planetary gear and the driving and driven plates are arranged one behind another along the axial line of the transmission. The diameter of automatic transmissions can be reduced by employing this arrangement. This arrangement, however, requires a clutch drum which is long in the axial direction and has long spline grooves It is very difficult to make long spline grooves by press forming.